This invention relates to electric power use controllers at an electric power subscriber's premises that monitor power uses at the premises and control them, and more particularly to such power control systems that control power use according to a predetermined program.
A typical load profile of an electric Power Company that supplies industry, business and dwellings over a twenty-four hour period is shown in FIG. 17. Such profiles usually reveal an on-peak period beginning early in the morning at a level of, for example, 8,000 Megawatts, rising to a level of about 12,000 Megawatts by 11 o'clock AM and then dropping steadily to a level of about 11,000 Megawatts at mid afternoon, only to rise again to the level of 12,000 Megawatts again by 7 PM and thereafter drops throughout the evening and into the early hours of the next day to the 8,000 Megawatt level. Thus, there are two peaks during the day, one at about 11 AM and the other at about 7 PM; and during the off-peak period between 11 PM and 6 AM the next morning, the level falls well below 10,000 Megawatts.
This load profile tends to hold for most days of the year, although a load bias is imposed on particularly hot days when a great deal of air conditioning is demanded and on particularly cold days when electric heat demand is high. During such hot days, the total twenty-four hour period may be on-peak, inasmuch as at all times the load profile is above the 10,000 Megawatt level. It is one object of the present invention to provide a monitoring and control system for use in a subscriber's premises for controlling the several types of uses of electric power in the premises so that the premises uses electric power during the off-peak periods, where possible, rather than during the on-peak periods, without undue loss of subscriber comfort.
Power Companies presently lose millions of dollars each year from the theft of power by subscribers and those who have access to the power lines. The present method of monitoring and verifying power use by industrial subscriber's typically involves electronic meters with a remote sensing ability. Such meters are polled remotely via modems on existing phone lines. Currently, such remote sensing and polling systems are relatively expensive and are used only for industrial subscribers and not for dwellings or small businesses. Furthermore, such systems used for industrial subscribers have not been programmed with any particular effort to reduce power use during on-peak periods, or to spread power use over off-peak periods so that the Power Company load is spread more evenly over a twenty-four hour period.
These power control systems for industrial subscribers have been used primarily to inhibit theft of energy and have not been used to promote more economical use of energy or to help the Power Company achieve a more even load. Spreading the power loads of industrial subscribers more evenly over a twenty-four period, for many Power Companies, would not have much effect on the Power Company's load profile. The reason for this is that for most Power Companies, by far the greater power load is not by industry and business, but by homes and dwellings. These prior monitoring systems used by industrial subscribers are too expensive for use in homes and dwellings. It is another object of the present invention to provide a relatively low cost controller for use in a home that is effective to shift several power uses therein from on-peak periods to off-peak periods without undue loss of subscriber comfort; and thereby spread power loads in the home more evenly over the twenty-four hour day, and at the same time provide monitoring by the Power Company to inhibit power theft. Such a controller installed and operating in a large percentage of the dwellings serviced by a typical Power Company would have a very considerable impact on the daily load profile of the Power Company and would reduce and spread the on-peak loads.
A Power Company would much prefer to reduce the on-peak loads even at the expense of raising the off-peak loads and so flatten the profile. At the present time, many Power Companies are unable to meet the highest on-peak loads from their own generating facilities and so must buy the power from other generating facilities and the cost is usually greater. Hence, Power Companies have for some time been seeking methods and means of controlling electric power uses in subscriber's homes and dwellings, because that will result in reducing on-peak loads and still supply the subscriber's needs.